The thin aluminum nitride(AlN) film using as an insulating layer was inserted between the anode (ITO) and the NPB
organic film in the organic light-emitting devices(OLED) for the structure being K9/ITO/AlN/NPB/Alq<sub>3</sub>/LiF/Al.The
effect of the different thickness AlN film on the device performance was investigated. After optimization, improvement
of OLEDs properties is biggest when the AlN film thickness is about 0.4nm.Such a structure with AlN layer facilitates
the increase of current density and decrease of threshold voltage, resulting in an improved luminance and energy
efficiency. The average luminance increased by about 30% and an improvement of 21.8% on the average current density.
The lifetime experiment of the devices has proved an improvement on stability because of inserted AlN film. This
phenomenon is mainly because of the insulating capability of the aluminum nitride coating and the passivation role of
AlN film to the ITO surface. The processing is simple and high efficient, can be widely applied to the OLED devices.